Magister Chirurgiae Dentium (MChD) / Wound healing is a complex process characterised by the repair and reconstitution of lost or damaged tissue. By the mid 1990s, several methods were proposed to enhance wound healing of surgical sites by introducing high concentrations of human platelets to these areas. In the early 21st century, Choukroun et al (2006b) introduced a new type of platelet concentrate that was devoid of any additives, and required no specialised equipment for its production. This concentrate was termed Platelet-rich fibrin (PRF) and although various aspects of this biomaterial had been studied, very little is currently known about its storage properties. Aim: To determine whether storage time had a significant effect on the platelet concentration of Choukroun’s PRF Method: A total of 30 patients were enrolled into the study. Three blood samples of 10ml each were drawn from each patient. Two of the blood samples (Group A and Group B) were centrifuged to form PRF. The third sample was used to measure the baseline blood platelet concentration and was therefore not centrifuged. After PRF had formed in both test groups, it was removed from the test tubes at 2 different times i.e. immediately after centrifuge (Group A) or after 60 min of storage in the blood collecting tube (Group B). The remaining blood was then tested for platelet concentration and compared to each other and the baseline reading. Results: 14 males and 16 females participated in the study (average age 41.7 years). A mean blood platelet concentration of 282.8 ± 58.3 × 109/L was recorded for the baseline reading. Group A had a mean blood platelet concentration 7.9 ± 3.03 × 109/L. Group B had a mean blood platelet concentration of 4.0 ± 1.93 × 109/L. A statistically significant difference was seen between Groups A and B (p < 0.0001). Conclusions: Storage time has a significant effect of the platelet concentration of PRF. If stored over a period of 60 min, the platelet concentration of PRF increases. Further research is required to determine whether this finding is clinically significant.

Background: Conjunctival pedicle flaps are one of the most frequently employed surgical interventions used to address a variety of sight threatening corneal diseases in veterinary ophthalmic practice. Securing the conjunctiva to the cornea is typically achieved through suturing, which is technically challenging and can result in prolonged surgical times, increased corneal edema, increased scar tissue, foreign body reaction, suture abscess and dehiscence. In human ophthalmology, a number of sutureless techniques to affix ocular tissues are being explored. Specifically, these approaches include synthetic tissue adhesives, bioadhesives, and hydrogel sealants. The proposed advantages of adhesives over suture, include reduced operative times, watertight seals, decreased foreign-body sensation and inflammation, faster healing times and tissue regeneration with original architecture restoration. Objective. To evaluate the maximum tensile force a conjunctival pedicle flap is able to withstand with respect to different fixation methods, i.e., Tisseel® fibrin glue, ethyl cyanoacrylate adhesive, ReSure® hydrogel sealant, or 8-0 VICRYL suture. Animals Studied. Ex-vivo porcine globes Procedures. Following a 500-micron restricted depth lamellar keratectomy, conjunctival pedicle flaps were dissected and secured to corneal defects with either the bioadhesive Tisseel®, or the synthetic adhesives ReSure®, ethyl cyanoacrylate, or 8-0 VICRYL® suture. Harvested corneoconjunctival flap interfaces were clamped to an accelerometer and potentiometer device, and loaded under video surveillance until the point of failure. Peak load at failure was determined for each test and used to compare between sample types. Results. 40 flaps underwent tensile force testing, with 6 being omitted for dehiscence prior to tensile testing. Of the 34 tests included in analysis, 10 conjunctival flaps were secured with suture, 10 with cyanoacrylate, 8 with ReSure® hydrogel sealant, and 6 with Tisseel® fibrin glue. A significant increase in maximum withstood tensile force was recorded between sutured flap fixation when compared with cyanoacrylate glue (p=0.02474), ReSure® hydrogel sealant (p= 0.00000), and Tisseel® fibrin glue (p= 0.00002). Cyanoacrylate fixation was significantly stronger when compared with ReSure® hydrogel sealant and Tisseel fibrin glue (p=0.01194 and 0.01798 respectively). There was no significant difference in adhesion strength between ReSure® hydrogel sealant and Tisseel® fibrin glue (p=0.95675). Conclusions. Conjunctival pedicle flap fixation using 8-0 VICRYL® suture fixation was able to withstand significantly greater maximum tensile force application in comparison with the ReSure®, Tisseel®, or cyanoacrylate adhesives. / Master of Science / Conjunctival pedicle flaps are one of the most frequently employed surgical interventions to address sight threatening corneal disorders in companion animals. Due to its redundant nature and close proximity to the corneal surface, conjunctival tissue is readily available for grafting to the cornea. It is surgically dissected to appropriate size and repositioned over the corneal defect where it effectively aids in healing through direct provision of structural support and indirectly via its rich blood supply. Securing the conjunctiva to cornea is typically achieved through suturing, which is technically challenging and can result in prolonged surgical times, increased corneal edema, increased scar tissue, foreign body reaction, abscess and dehiscence. In human ophthalmology, a number of sutureless techniques to affix ocular tissues are being explored. Specifically, these approaches include synthetic tissue adhesives, bioadhesives, and hydrogel sealants. The proposed advantages of tissue adhesives over suture, include reduced operation times, watertight closures, decreased foreign-body reaction and inflammatory response, faster healing times and increased ability to induce regeneration of the original tissue architecture. The purpose of this study was to evaluate the maximum tensile force a corneoconjunctial pedicle flap is able to withstand with respect to four different fixation methods, 40 ex-vivo porcine globes underwent conjunctival pedicle flap procedures. Each pedicle flap was secured to cornea with either 8-0 Vicryl® suture, Tisseel®, ethyl cyanoacrylate, or ReSure®. After harvesting from the globe, the corneoconjunctival unions were clamped to an accelerometer and potentiometer device, and loaded under video surveillance until the point of failure. The peak load was determined for each test and used to compare between sample types.

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名古屋大学博士学位論文 学位の種類 : 博士(医学)(論文) 学位授与年月日:平成3年2月1日 服部寿門氏の博士論文として提出された